The best answer I’ve heard is that they don’t because it doesn’t actually serve their ends. Their purpose is only partly to instill public terror in Americans. They also need to raise money, and recruit more terrorists. Those people don’t want to hear that you really scared the hell out of Plano, Texas. They want to hear that you bombed Times Square. Their target market, in other words, is not just Americans; it’s the folks at home.

And this is also true of domestic terrorism. You could sow a lot of fear in federal employees by randomly kidnapping them and killing them, one at a time, then leaving a note explaining what you’d done. It’s not like the federal government could afford 24-hour surveillance on every postal worker and passport clerk in the land.

But that’s not part of the self-image that these sorts of psychopaths cultivate. They’re trying to touch off a revolution, not scare the bejeesus out of the portfolio managers at the FHA. And to start a revolution, you need a bona fide act of war.

Thank God for small favors. If all they really cared about was terrorising us, we’d be terrified, because they’d be mounting the kind of undetectable, untraceable attacks that can kill hundreds, a few at a time. Instead, they’re still trying to top 9/11 and Oklahoma City.